The invention relates to the reduction of the corrosiveness of oxygen-containing water. It further relates to post-primary oil recovery processes involving the introduction of water into an underground formation.
In certain large-scale uses of water for industrial purposes, it is economically necessary to use naturally-occurring water near the site of the application. Such naturally-occurring water will often contain high concentrations of salts and dissolved oxygen. Such highly-oxygenated water is corrosive to any metal equipment with which it comes in contact, adding significantly to the expense of the process.
An example of such a process is the post-primary recovery of oil using various water-flooding procedures. The large quantities of water involved make it necessary to use naturally-occurring brine, the high salt content of which makes it corrosive to the down-well metal drilling equipment. The problem of corrosion is particularly great in off-shore oil drilling sites, where the sea water employed for flooding the formation is highly corrosive.
Oxygen-consuming enzyme systems can be used to deoxygenate such water and reduce its corrosiveness. For example, alcohol oxidase enzymes, which catalyze the reaction of an alcohol with oxygen to produce an aldehyde and hydrogen peroxide, can be added to oxygen-containing water in combination with a suitable alcohol substrate to reduce the oxygen content of the water. It has been found that the reduction of the oxygen content of highly-saline water is not adequate for some purposes to sufficiently reduce corrosion, possibly because of the production of by-products which are themselves corrosive.
It would be desirable to reduce the corrosiveness of brine by deoxygenaton to a sufficient extent to render the brine useful for a variety of purposes in which the brine comes in contact with corrodible surfaces.
It is therefore an object of the present invention to provide a method for reducing the corrosiveness of aqueous fluids used in processes in which the fluids come in contact with corrodible surfaces.
It is a further object to reduce the oxygen content of brine.
it is a further object to provide an improved method of post-primary oil recovery in off-shore oil wells.